1
Foundations in Orbit
1998-2000The earliest station elements established structural connections, propulsion, electrical power, docking capability, and the core systems needed for permanent orbital assembly.
Spacecraft Engineering
ISS Engineering Breakdown
Module timeline, deployment vehicles, schematics, and connected content.
The International Space Station is the largest modular space station ever assembled in orbit and one of the most complex engineering projects in history. Its development brought together earlier American, Russian, European, Japanese and Canadian space-station programs. Five partner agencies—NASA, Roscosmos, ESA, JAXA and CSA—contributed to the station. The first element, Zarya, launched on 20 November 1998, and continuous human habitation began in November 2000. Since then, the ISS has served as an orbiting laboratory for human health, biology, materials science, technology demonstrations, Earth observation and preparation for longer journeys beyond Earth.
Interactive Engineering Schematic
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Engineering Detail
Zarya
Functional Cargo Block
Added 1998
Zarya formed the first orbital foundation of the International Space Station. The Functional Cargo Block supplied electrical power, propulsion, attitude-control capability, communications, and storage during the earliest assembly phase before later ISS systems assumed many of those duties.
Launch & Installation History
Launch
November 20, 1998
Installed / Docked
November 20, 1998
Mission
Zarya Launch
Vehicle
Proton-K
Launch site: Baikonur Cosmodrome
Specifications
Role
Functional Cargo Block
Segment
Russian
Added
1998
Engineering Storyline
How the spacecraft came together
2
Assembly & Utilities
2000-2006Truss structures, electrical-generation systems, thermal-control hardware, robotics, and docking infrastructure transformed the first modules into an expanding orbital complex.
3
Laboratory Expansion
2001-2011New laboratories, connecting nodes, logistics modules, and observation systems expanded the station's scientific capacity and usable internal volume.
4
Modern Upgrades
2011-PresentReplacement systems, new research hardware, and additional modules continue to expand the station's capabilities and extend its operational life.
Component Engineering
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Engineering Specifications
Object Type
Modular orbital space station
Orbit
Low Earth orbit
Assembly Began
1998
Continuous Habitation
2000-present
Science & Operations
The ISS remains in orbit because it travels sideways around Earth fast enough that, while gravity continuously pulls it downward, Earth's curved surface falls away beneath it. Using the TransitSatellite catalog altitude of approximately 416 km (259 mi) as an idealized circular orbit, its estimated speed is 7.66 km/s, 27,574 km/h, or about 17,134 mph.
At that representative altitude, one orbit takes approximately 92.9 minutes. That equals about 15.5 orbits per day, with an estimated orbital circumference of approximately 42,689 km (26,526 mi). The station's real altitude, speed and orbital period change as atmospheric drag, reboost maneuvers, visiting spacecraft and other perturbations affect its orbit.
Microgravity does not mean that gravity has disappeared. The ISS and everything inside it are falling together around Earth, creating continuous free fall. This environment allows researchers to study processes such as fluid behavior, combustion, crystal growth, plant development, materials and changes to the human body with greatly reduced effects from weight.
Constructing and operating the ISS requires orbital rendezvous, docking, attitude control, electrical-power management, thermal control, communications, life support, robotics and repeated cargo and crew missions. Spacecraft approaching the station must carefully match its orbital plane, altitude, timing and relative velocity before docking.
Launch & Deployment
ISS assembly began when the Russian-built Zarya control module launched aboard a Proton-K rocket from Baikonur Cosmodrome on 20 November 1998. The Unity connecting module followed aboard Space Shuttle Endeavour in December 1998. The first long-duration residents—Expedition 1—arrived in November 2000. The station was assembled through dozens of missions carrying laboratories, habitation modules, trusses, solar arrays, robotic systems and other equipment. Its launch story is therefore not one launch but an international construction campaign conducted in orbit over many years.
Build Timeline